Apparatus for fabricating finned tubing



May 4, 1965 R. J. GARLAND APPARATUS FOR FABRICATING FINNED TUBINGOriginal Filed March 27. 1957 2 Sheets-Sheet 1 INVENTOR. ROBERT J.GARLAND AT TURNEY May 4, 1965 R. J. GARLAND APPARATUS FOR FABRICATINGFINNED TUBING Original Filed March 27. 1957 2 Sheets-Shet 2 FIG. 4-

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ATT URNEY United States Patent M APPARATUS FUR FABRICATING FINNED TUBINGRohert .3. Garland, De Witt, N.Y., assignor to Carrier Corporation,Syracuse, N.Y., a corporation of Delaware Original application Mar. 27,1957, Ser. No. 648,940, new

Patent No. 3,000,084, dated Sept. 19, B61. Divided and this applicationNov, 30, I960, Ser. No. 72,610

Claims. (ill. 29-56l) This application is a division of my copendingapplication Serial No. 648,940, filed March 27, 1957, now United StatesLetters Patent 3,000,084, issued September 19, 1961, entitled Apparatusand Method for Fabricating Finned Tubing and relates to a finningmachine for forming a plurality of helically extending fin about a tube,and more particularly, to a machine by which a plurality of fins may behelically wound around a tube and secured thereon in a single operation.

Finned tubing is perhaps the most popular type of heat exchange surfacepresently being used. Although this type of tubing is relativelyinexpensive, a major factor in its low price resides in its productionin large quantities. The machines that manufacture finned tubingcomprise a substantial investment and yet because of the tremendousamount of this surface that is used, they can easily be renderedobsolete by machines capable of producing similar surfaces at aninsignificant fraction of a cent less per length than existing machines.

The present invention is concerned with apparatus for applying a dualfin to a tube without exceeding the complexities of a normal single finmachine. In this manner production of finned tubing may be substantiallyincreased with the capital investment of a single fin machine therebymaterially reducing the cost of this type heat exchange surface.

The chief object of the present invention is to provide an apparatus formaking a more inexpensive finned tube.

An object of the present invention is to provide an apparatus forforming a single ribbon dual fin on a tube.

Another object is to provide an apparatus for placing a plurality offins on a tube of a thickness substantially less than presentlycommercially used.

A further object is to provide an apparatus for applying a single ribbondual fin to a tube by folding a single ribbon of metal to a doublethickness, winding the strip so formed on the tube as a single fin andthen separating and spacing the portions of the strip into a double fin.Other objects of the invention will be readily perceived from thefollowing description.

This invention further relates to an apparatus for winding a pluralityof fins about a rotating and advancing tube comprising in combination,means for creasing the center of a ribbon, means for folding the equalsections of the ribbon on both sides of the crease into face-to-faceengagement. Forming rolls wind the folded ribbon into a helix about thetube with the fold adjacent the tube, and spacing discs separate thesections of the ribbon and widen the fold adjacent the tube.

The attached drawings illustrate a preferred embodiment of theinvention, in which FIGURE 1 is a diagrammatic view illustrating thefinning machine of the present invention;

FIGURE 2 is a view in elevation, taken in a plane normal to the centerline of the head of the machine illustrating the winding of the ribbononto the tube;

FIGURE 3 is a view in elevation similar to FIGURE 2, however, indicatingthe position of the spacing disc with respect to the tube and ribbon;

FIGURE 4 is a view in elevation illustrating the operation of the guideand spacing rolls;

FIGURE 5 is a view similar to FIGURE 4, however,

idhliiifi a, was

Patented fv'lay indicating the guide and ribbon in section therebyillustrating the action of the forming rolls; and

FIGURE 6 is an enlarged sectional view illustrating the action of thespacing discs.

Referring to the drawings, there is shown in FIGURE 1 a ribbon 2, whichoriginates from a spool of material not shown. The ribbon is fed overthe pulley 3 through a slot type guide 4, which directs the ribbonbetween the folding rolls 5 and 5, these folding rolls place a creaselongitudinally and substantially in the center of the ribbon 2. Theribbon is passed from these first folding rolls 5 and 6, to the secondfolding rolls '7 and 8, in which the angle of the initial fold isaccentuated. The ribbon is fed from the folding rolls 7 and 8 to theroller guide 9, which is in engagement with the folded end of the ribbonand is adjacent the rolls l0 and II. The rolls ill and 11 urge thefolded sections of the ribbon 2 into face-to-face relationship throughthe slot guide 13 which passes the folded ribbon to the finning machineproper.

The finning machine proper includes a head Ztl which includes aconventional mechanism to rotate the tube 17 while simultaneouslyadvancing the tube. This head may also include suitable rolls such as21. These rolls are knurled to roughen the surface of the tube prior tothe application of the ribbon thereon. In some heads this rougheningfunction may be performed by the knurled rolls which grip the tube aspart of the advancing and rotating mechanism.

This particular head, it will be noted, should be of the type whereinthe horizontal forming roll 15, the vertical forming roll 16 and therotating and advancing tube mechanism are mechanically connected withsuitable slip-clutch means between the advancing mechanism and therotating mechanism for allowing desirable lost motion therebetweenduring the firming operation.

Referring to FIGURE 2, the forming rolls l5 and I6 are shown with thefolded ribbon 2 being passed under a portion of the guide 14. This guide14 defines a surface having a general helical convolution. The formingrolls l5 and la grasp the fin and wind it about the tube I7. After thefin leaves this winding section, it is urged away from the surface ofthe roll 15 by the guide 14, which guides the fin in a helical path tothe rear of the vertical forming roll 16, and then to the spacing rollsor discs 13 shown in FIGURE 1.

FIGURE 3 illustrates an end view of the machine looking toward the head.This view shows the location of three sets of spacing discs 18, 24 and2'5. It will be noted that these discs are located on intervals for thepurpose of adequately spacing and supporting the during the formingoperation which will be more fully described hereinafter.

Referring to FIGURE 4 there is shown a side view of the finningapparatus shown in FIGURE 3. In this view, the ribbon in its foldedface-to-face orientation is shown being rolled through the forming rollsl5 and I6, and then being guided by the contour of the guide 14 to therear of the forming roll 16. The fin then enters into the zone whereinare located the various spacing discs. Generally these discs firststraighten the double fins, separate the fins and then increase thecontact between the fins and the tube.

FIGURE 5 is a view similar to FIGURE 4, however, the fin and guide 14are shown in section and the view is enlarged. In this particular view,the shape of the fin is clearly indicated, the manner in which it passesthrough the forming rolls l5 and I6 is shown. The contour of the guide14 may be better understood from this view and its function more easilyappreciated.

FIGURE 6 illustrates an enlarged section of the tube, fins and spacingdiscs, and further illustrates the progre sive forming of the fins bythe disc. Discs Ell-36 are support discs and discs 44' 41 and 42 areseparating discs. The function of the supporting discs is merely tospace and maintain the position of the fins whereas the function of theseparating discs is to space the two fins comprising the ribbon and toincrease the contact between the fold of the ribbon and the tube.

Considering the operation of the present invention, the ribbon 2 ispassed over the pulley 3 through the slot guide 4 and through thefolding rolls 5 and 6 and 7 and 8. These rolls form a longitudinalcrease in the center of the ribbon and the rolls 10 and 11 urge the legportions 2' and 2" of the ribbon into face-to-face engagement.

The ribbon 2 is then passed into the slot guide 13 which directs theribbon through the forming rolls 15 and 16. These forming rolls wind theribbon 2 onto the tube 17 and the guide 14 directs the ribbon so appliedin a general helical path about the tube 17. The ribbon, at this point,is in substantial mechanical engagement with the tube. Referring toFIGURE 4, the general path of the ribbon is illustrated from the pointwhere it emerges from the forming rolls until it passes from the spacingdiscs.

Referring to FIGURE 5, this sectional view illustrates the angulardisposition of the ribbon after it has been wound on the tube and it isnoted that the fin on the rear side of the forming roll 16 is angularlydisposed with respect to the tube 17. In some cases where a high fin isdesired, it may be found desirable to have the fin as straight aspossible on the pass of the ribbon at the rear of the vertical formingroll 16. To facilitate this condition the forming roll surfaces and axesorientations may be such that the angle between the axes of the formingrolls is less than 90. With such a situation the ribbon will be passedto the forming rolls at a considerable angle, however on the rear sideof the roll 16 just prior to entrance into the spacing discs, the ribbonmay be almost perpendicular to the tube.

Referring to FIGURE 3, it will be noted that the ribbon is passedthrough three sets of spacing discs. These discs may be motor driven ifdesired. The number of sets of discs and their configurations may bevaried. The number of sets of discs is determined by the amount ofsupport the ribbon and tube require. This is further affected by thesize of the separating discs which spread the folded portions of theribbon. Should the separating step be abrupt, the ribbon will requiregreater sup port and more sets of spacing discs are necessary.

FIGURE 6 shows a sectional view of the finning operation illustratingfully the progressive forming of the fin terminating with the final stepwherein the dual fin is urged against the tube in such a manner as toincrease the surface contact between the fin and the tube.

The fin passes from the guide 14 into the space A which lies between thesupport rolls 30 and 31. In this particular space the fin is at an angleto the surface of the tube 17. The fin passes through adjoiningcomplementary discs until it is straightened with respect to the surfaceof tube 17 and is substantially perpendicular thereto, as shown in thespace B between the discs 31 and 32. This function is continued in spaceC between discs 32 and 33. The essential function of these support discsis to confine the movement of the fin.

As the fin passes around the tube 17 the separating disc 4%) separatesthe legs 2' and 2 of the ribbon 2. It will be noted that this action isa progressive one. The sides of the ribbon are constrained by thesupport discs 33 and 34. It will be noted that by this action the heightof the fin is slightly decreased over the height of the fin in the spaceC. The separating disc 40 at its periphery has two surfaces at an anglewith respect to the side walls of the disc. The peripheral portion ofthe disc has a slight land. The function of this particular disc is tostparate the folded fin into the ultimate double fin construction.

It will be appreciated that in the original forming operation the foldedfin was placed in substantial mechanical engagement with the tube 17. Asthe fin passes through the various discs, this mechanical engagement andthe amount of surface contact between the fin and the tube tends toreach a maximum condition. The fin continues to rotate and advance inaccordance to the action of the aforementioned head and enters in thespace between the support discs 34 and 35.

Between these discs there is located the separating disc 41. This discis similar to the disc 40. However, at the periphery of the disc theangle of the tapered surfaces is increased as compared to the angle usedon disc 40. This angle is more abrupt for the purpose of bringing moreof the folded area of the fin into surface contact With the tube 17.

In bringing more surface into contact with the tube 17, it will beappreciated that this contacting surface area of fin is obtained at theexpense of the legs 2 and 2,". Therefore, the height of the fin betweenthe support discs 34 and 35 is less than the height of the two previouspasses of the fin through the spacing discs. The tube continues torotate and advance and is finally passed between the spacing discs 35and 36 which have located therebetween the separating disc 42. This discis physically similar to the separating disc 41 of the previous pass. Itwill be noted that this last separating disc merely emphasizes the fincontour created by the separating disc 41.

It will be noted that the initial separating disc 40 keeps the legs ofthe fin in substantial parallelism. However, the fold in the ribbon isgiven a pronounced V- shape. The subsequent pass of the separating discsmodified this V-configuration to a general U-shape. This U-shaped foldincreases the amount of surface contact between the tube and the finwhich will greatly enhance the heat transfer between the tube and thefin.

In considering FIGURE 1 it will be noted that the knurling rolls 21 areutilized to score or roughen the surface of the tube 17 prior to thefinning operation. It will be appreciated that this is an optional stepwhich will greatly increase the surface contact between the fin and thetube. The roughened surface permits the fin to come into more intimatecontact with the tube which results in a tighter fin With a bettermechanical bond to the tube and with consequent improved heat transferproperties.

In the present invention, due to the fact that the ribbon is applied tothe tube in a manner similar to a single fin machine, the totalthickness of the folded fin may be of a thickness comparable to that ofa normal single fin. Therefore, the ribbon initially supplied may beconsiderably thinner than the stock used on single fin machines. In thismanner a fin is applied much thinner than was physically possiblepreviously which results in a cheaper and lighter heat exchanger.

While I have described a preferred embodiment of the invention it willbe understood that the invention is not limited thereto since it may beotherwise embodied within the scope of the following claims.

I claim:

1. In an apparatus for Winding a ribbon about a rotating and advancingtube, the combination of means for placing a longitudinal crease in aribbon, means for placing the folded legs of the ribbon intoface-to-face engagement, forming rolls for winding the folded ribbonabout the tube with the fold adjacent the tube and discs for separatingthe legs of the folded ribbon from face-toface contact.

2. In an apparatus for winding a ribbon about a rotating and advancingtube, the combination of means for placing a longitudinal crease in theribbon so as to define substantially equal legs, means for placing thefolded legs of the ribbon into face-to-face engagement, forming rollsfor winding the folded ribbon about the tube with the fold adjacent thetube, guide means for urging the ribbon into a substantially helicalpath, support discs for straightening and spacing the ribbon on the tubeand separating discs for separating the legs of the ribbon from theface-to-face contact.

3. The apparatus according to claim 2 wherein separating discsprogressively widen the fold in the ribbon to substantially increase thesurface contact between the ribbon and the tube.

4. In an apparatus for Winding a ribbon about a tube, the combination ofmeans for rotating and advancing the tube, means for roughening thesurface of the tube, means for placing a longitudinal crease in a ribbonsubstantially defining two equal legs, means for placing the folded legsof the ribbon into face-to-face engagement, forming rolls for windingthe folded ribbon about the tube with the fold adjacent the tube, guidemeans for urging the ribbon in a substantially helical path, supportdiscs for straightening and spacing the ribbon on the tube andseparating discs for separating the legs of the ribbon from face-to-faceengagement and progressively widening the fold in the ribbon to increasethe surface contact between the ribbon and the tube.

5. In an apparatus for winding a ribbon about a rotating and advancingtube, the combination of means for feeding a folded ribbon to the tube,forming rolls for winding the folded ribbon about the tube with the foldadjacent the tube and a plurality of discs for spacing the ribbon on thetube and separating the folded legs of the ribbon.

References Cited by the Examiner UNITED STATES PATENTS 2,363,224 11/44Bronander 153--645 2,416,865 3/47 Bronander 1532 2,800,944 7/57Schmeling 15364.5

CHARLES W. LANHAM, Primary Examiner.

WHITMORE A. WILTZ, Examiner.

1. IN AN APPARATUS FOR WINDING A RIBBON ABOUT A ROTATING AND ADVANCINGTUBE, THE COMBINATION OF MEANS FOR PLACING A LONGITUDINAL CREASE IN ARIBBON, MEANS FOR PLACING THE FOLDED LEGS OIF THE RIBBON INTOFACE-TO-FACE ENGAGEMENT, FORMING ROLLS FOR WINDING THE FOLDED RIBBONABOUT THE TUBE WITH THE FOLD ADJACENT THE TUBE AND DISCS FOR SEPARATINGTHE LEGS OF THE FOLDED RIBBON FROM FACE-TOFACE CONTACT.